The best borescopes let you get a good look inside your home's walls to see pipes, wires, and other hard-to-see parts. See ...

This relay type is typically used for small- to medium-diameter borescopes. A visual comparison of GRIN vs. Hopkins relays. Note that both relays produce the same optical output by different means.

The best borescopes let you get a good look inside your home's walls to see pipes, wires, and other hard-to-see parts. See ...